In a general blood purification treatment such as dialysis treatment, a blood circuit formed of a flexible tube is used for extracorporeal circulation of the blood of a patient. The blood circuit includes an arterial blood circuit to the distal end of which an arterial puncture needle for collecting blood from the patient is attached, and a venous blood circuit to the distal end of which a venous puncture needle for returning the blood to the patient is attached. A dialyzer is provided between the arterial blood circuit and the venous blood circuit, and a blood pump is provided to the arterial blood circuit. Thus, the blood purification treatment is performable while the blood is extracorporeally circulated.
Prior to the blood purification treatment, the distal end of the arterial blood circuit and the distal end of the venous blood circuit with the arterial puncture needle and the venous puncture needle yet to be connected thereto are connected to each other, whereby a closed circuit is formed. Then, priming in which the closed circuit is filled with a priming solution is performed. To perform the blood purification treatment, the arterial puncture needle and the venous puncture needle are stuck into an access vessel of the patient, and the distal end of the arterial blood circuit and the distal end of the venous blood circuit that have undergone priming are connected to the arterial puncture needle and the venous puncture needle, respectively. Then, the blood pump is activated for blood removal. Such a technique has not been disclosed by any publicly known teaching, and there is no information on patent literature to be cited.